Electromagnetic device and method for the geometric rectification of stamped metal parts

ABSTRACT

The invention relates to an electromagnetic device and a method for the geometric rectification of stamped metal parts comprising at least one block having a surface with a final geometry which is intended to be obtained in one side of an area to be rectified of a part, which is positioned between said block and a complementary electromagnetic coil comprising at least one winding configured to generate a magnetic field configured to act on the part and produce its impact against said block, there being a space between each electromagnetic coil and each block not greater than ten times a thickness of the part, with the aim of being able to move the part by the action of the magnetic field.

OBJECT OF THE INVENTION

The present invention relates to an electromagnetic device and a methodfor the geometric rectification of stamped metal parts havingapplication in the iron and steel industry, allowing to rectify thedeformation produced by elastic recovery as a result of the residualstress generated in this type of parts in the form of sheets aftercarrying out a mechanical forming process, for example after a flangingprocess.

BACKGROUND OF THE INVENTION

The conventional stamping process of metal sheets requires the use of apress and at least two dies, a drawing die and a calibrating die, eachof which is in turn formed by a complete hold-down plate, female elementand male element having all the geometry, shape and dimensions desiredin the sheet to be formed.

The drawback with mechanical stamping processes occurs after removingthe parts from the press, due to the fact that they undergo an elasticrecovery producing deformations, wall curls, and torsions as a result ofthe residual stress generated in the parts after the drawing process,with which the geometry of the part is different from the one that isdesired.

The drawback mentioned in the previous paragraph is usually known as“springback” and it results in the obtained parts being out of theestablished tolerances, which are very strict especially in certainapplications such as in the automation field or on the aeronauticalfield, therefore, there is a need to rectify the geometry of the partsobtained after the drawing process.

With the aim of solving this drawback, after carrying out the mechanicaldrawing process it is necessary to carry out a reforming of the completepart in a calibrating die, in which the rectification of those areas ofthe part that are out of the admissible tolerances after the mechanicaldrawing process is achieved, which significantly increases theproduction costs of the parts.

On the other hand, with the aim of solving this same drawback, startingfrom 1960, alternative forming processes appeared comprisingelectromagnetic circuits and means capable of generating enough currentsto produce a deformation in the material, in substitution of thetraditional presses usually used to date, as set forth previously.

These electromagnetic forming processes are based on generating amagnetic field by means of electromagnetic coils inducing Foucaultcurrents in the part or sheets to be formed, said Foucalt currentshaving the opposite direction to the currents circulating in eachelectromagnetic coil, therefore, the coil and the metal part repel eachother such that the part is driven against the wall of the dies,adopting the desired shape, i.e. the shape of the dies, which coincideswith the final geometry of the complete part which is intended to beobtained.

The aforementioned electromagnetic forming devices currently comprise aconductor, also denominated actuator, which is usually a copper solenoidcoil connected in series with a capacitor, or usually a capacitor bank,and with a high voltage circuit and trigger start means.

The operation of these devices is explained below. When the capacitorsare charged and switched on, i.e. the circuit switch connecting it tothe electromagnetic coil is closed, a transient current is created insaid electromagnetic coil, which generates a transient magnetic fieldinducing Foucault currents in the conducting material which is the metalpart that is intended to be deformed.

A representation of the discharge current usually used has a dampedsinusoidal shape, with frequencies that are usually in a range between10 kHz and 100 kHz. The current generated in the electromagnetic coiland the currents generated in the part have opposite directions,therefore, the coil and the part repel each other such that the partacquires a high repulsion velocity and is driven against a male orfemale part adopting its shape. The electromagnetic pressure isconverted into kinetic energy, the part being able to acquire velocitiesof an order of magnitude between 200 m/s and 300 m/s.

These electromagnetic forming processes have been the object of variousstudies by several authors which are gathered in different documents,such as for example in the following articles:

-   Golovashchenko, Sergey F. ‘Springback calibration using pulsed    electromagnetic field’; © 2005 American Institute of Physics.-   Moon, F. C. ‘Magneto solid mechanics’; ASTME; High Velocity Forming    of Metals; 1968.-   Plum, M. M. ‘Electromagnetic forming. Metals handbook’; Maxwell    Laboratories Inc. Pages 644-653.-   Belyy, I. V., Fertik, S. M. and Khimenko, L. T. ‘Electromagnetic    metal forming handbook Kharkov’; USSR; 1977.

There are also patent documents describing these electromagnetic formingprocesses since the start of their development, such as for example U.S.Pat. No. 2,976,907 for “Device and method of metal forming”corresponding to 1961, up to more recent documents which gather thelatest means and applications, such as for example in U.S. Pat. No.6,050,121 for “Hybrid methods of metal forming using electromagneticforming” to the University of Ohio, in U.S. Pat. No. 5,730,016 for“Method and apparatus for electromagnetic forming of thin walled metal”to the company Elmag, Inc., in U.S. patent application No. 2005/0097934for “Conjoining apparatus using electromagnetic forming”, US patentapplication No. 2005/0229376 for “Electromagnetic trimming, flanging andhemming apparatus and method” to the company General Motors, US patentapplication No. 2003/0182005 for “Method for determining a die profilefor forming a metal part having a desired shape and associated methods”to Chu, E., Makosey, S. J. and Shoup, J. M. or in U.S. Pat. No.5,860,306 for “Electromagnetic actuator method of use and article madetherefrom” to Daehn, to name some examples.

Additionally, Japanese patents No. JP 2004-122177 and JP 2001-252788describe processes with presses for forming by stamping, incorporating amagnetic forming device which allows avoiding the springback effect.Japanese patent No. JP 2004-122177 describes a line of presses orequipment comprising a plurality of presses, commonly called “transfer”,containing at least an electromagnetic forming device in the pressitself with the aim of obtaining an aluminium part without elasticrecovery with a certain final geometry.

The main drawback of this type of equipment is that they are highlycomplex and expensive due to the need to incorporate electromagneticforming means in the stamping equipment itself, i.e., in the pressesthemselves.

The electromagnetic forming process is carried out simultaneously withthe stamping process, and this requires the use of expensive equipmentor the adaptation of existing stamping equipment, combining theelectromagnetic means with the stamping process itself, whichsignificantly increases the production costs of the parts.

Furthermore, although the sheets formed by means of the aforementionedelectromagnetic processes do not have the unwanted elastic recovery orspringback effect, these processes have another series of drawbacks,amongst other causes as a result of the high temperature that thegenerated magnetic field produces in the electromagnetic coil, needingto incorporate cooling means with the aim that the temperature of theelectromagnetic coil during the process is not too excessive and thusextending its working life, which is not necessary in mechanicalstamping processes.

DESCRIPTION OF THE INVENTION

The electromagnetic device and the method for the geometricrectification of stamped metal parts proposed by the invention allowscorrecting the deformation produced by the springback effect after aconventional forming process in an equipment independent of themechanical stamping equipment by means of applying electromagneticcharges only in those areas or parts of the part which require to berectified to obtain a part with a desired final geometry and inaccordance with established dimensional tolerances.

A first aspect of the invention relates to an electromagnetic device forthe geometric rectification of stamped metal parts which allowsrectifying the deformation produced by the elastic recovery as a resultof the residual stress generated in the parts after carrying out amechanical stamping process.

The electromagnetic device proposed by the invention comprises at leastone block configured to receive the impact and contact a side of acertain area to be rectified of a part, i.e., a sheet which has beenpreviously mechanically stamped in a press.

The geometry of a surface of said at least one block configured tocontact the part to be rectified corresponds exactly to a finalgeometry, i.e., shape and dimensions, which is desired in said side ofthe area to be rectified of the part.

Although, in the field of stamping, an element penetrating in a planedefined by the sheet is usually called male element, and a complementaryelement configured to house the deformed sheet by the action of saidmale element is usually called female element, in the description of thepresent invention, a block is considered to be any element such as amale element, a female element or an insert having the suitable geometryand being configured to receive the impact and contact the part to berectified.

In a complementary manner to each at least one block, the devicecomprises an electromagnetic coil which is configured to be located on aside opposite to said at least one block of a certain area to berectified of the part.

In the event that a block is located on a first side of the part, thenthe complementary electromagnetic coil is located on a second sideopposite to the first side, and vice versa, i.e., in the event that theblock is located on the second side of the part, then theelectromagnetic coil is located on the first side.

Each at least one electromagnetic coil comprises at least one winding ofa copper wire embedded in a part, preferably a synthetic body of glassfiber for example. Said electromagnetic coil has an outer surfaceopposite to a side of the part to be rectified having a geometryapproximate to the desired final geometry in the part, i.e., it has ageometry complementary to that of the at least one corresponding block,there being a space or clearance between each at least oneelectromagnetic coil and each at least one block that is less than tentimes the thickness of the part, with the aim that the action of themagnetic field drives the part for its impact against the block.

As mentioned previously, each at least one, electromagnetic coilcomprises at least one winding connected to a power supply sourceconfigured to generate a magnetic field.

Each at least one electromagnetic coil is operatively located such thatthe magnetic field it generates acts in a certain area to be rectifiedof the part, acting thereupon and producing an impact of the partagainst the corresponding block.

Each at least one electromagnetic coil is configured to act both on theplanar areas of the part and in the curved areas or folding lines, i.e.,in the areas in which the sheet has a change in direction betweenplanes.

In a stamped part, the joints between two sides thereof that arecontained in different planes have a certain radius, it being preferablyin these areas, at which the part is folded, in which the unwantedspringback effect occurs, an unwanted deformation being observed. Withthe aim of removing this deformation each at least one winding andelectromagnetic coil have a geometry approximate to the final geometryto be obtained, including a curved geometry.

With the aim of being able to generate the electromagnetic field each atleast one winding is connected to a discharge circuit comprising acapacitor, preferably a capacitor bank, and to a high voltage circuitcomprising a power supply source and trigger start means, i.e.,electrical switches, such that when the capacitors are charged and areactivated by means of the trigger start means, a transient current iscreated in each at least one winding generating the transient magneticfield.

Said magnetic field induces Foucault currents in the part to berectified due to the fact that the part is a sheet of electricalconducting material, the current generated in each at least one windingand the Foucault currents generated in the part having oppositedirections, therefore, the part is driven in the direction opposite tothat of each at least one electromagnetic coil, being pushed againstsaid at least one block such that the side of the areas to be rectifiedof the part in contact with said at least one block is formed acquiringthe geometry of said at least one block.

The possibility is considered that said at least one block andelectromagnetic coil are linked both at a first base and a second base,with the aim of serving as a support. Likewise, the possibility is alsoconsidered that said first base and said second base comprise moveableclosure means, the bases being able to be arranged in both a horizontaland a vertical position.

Finally, the possibility is contemplated that the device comprises atleast one driver located between said at least one electromagnetic coiland the part to be rectified, with the aim of reducing the energydemands of the device to obtain a certain geometry in a part to berectified.

Said driver consists of a sheet of material with a high copper content,so that, due to its high electrical conductivity, it makes it possiblefor the driver to generate induced currents of a greater intensity thanthose generated in the part, which is a sheet of material with a lowerelectrical conductivity. For this reason, the repulsion force betweenthe driver and the electromagnetic coil is greater with respect to thecase of not having said driver, allowing to obtain the same results witha lower energy demand.

On the other hand, a second aspect of the invention relates to a methodfor the geometric rectification of stamped metal parts with anelectromagnetic device like the one described previously.

The method of the invention is carried out starting from a metal part tobe rectified, i.e., a sheet which has already been mechanically stampedin a traditional press, with the aim of rectifying the geometry of thepart on those areas in which the part is out of the establishedtolerances. Unlike the methods of the state of the art, it is notintended to avoid the negative spring back effect of the part when thepart is stamped, but to correct it afterwards.

Therefore, the method for the geometric rectification of stamped metalparts object of the invention comprises the steps described below.

A first step comprises to place a stamped part with each area to berectified operatively located between a block and an electromagneticcoil, said part being conveniently separated from the block which isseparated from the complementary electromagnetic coil by a distance notgreater than ten times the thickness of the part, with the aim that thesaid part can impact against said block by the action of a magneticfield generated by said electromagnetic coil.

Then, the method comprises a second step comprising to generate amagnetic field configured to act in the areas to be rectified of thepart such that they adopt a required final geometry when the partimpacts against each block.

Finally, the method comprises a third step comprising to remove thealready rectified part.

The possibility is considered that the method comprises an intermediatestep which would be carried out before the second step of generation amagnetic field and comprising to place at least one driver, i.e. a sheetof material with a high copper content between said at least oneelectromagnetic coil and the part to be rectified, with the aim ofreducing the energy demands of the method.

The deformation of the metal part to be rectified is achieved by meansof the discharge of an electric current through said at least onewinding which is near the area to be rectified of the part. Due to thecurrents induced in the part, a quick movement of the area of the partnear the coil occurs. The kinetic energy associated with the movementoriginates the physical change in the part.

Therefore, according to the described invention, the electromagneticdevice and method for the geometric rectification of stamped metal partsproposed by the invention constitute a breakthrough in the formingdevices and methods used to date, and they fully and easily solve theaforementioned drawbacks in that they allow its use in any type ofsheets, whichever their forming process has been, allowing the regularexploitation and use of available stamping equipment such as for exampletraditional presses in a certain factory, i.e., without the need ofhaving to carry out any modification thereof, in order to later rectifythe parts in the device of the invention outside the press line only inthe cases in which it is necessary.

Therefore, the user can manufacture a part by means of a conventionalstamping process and in view of the result, can decide if it isnecessary to use the electromagnetic forming device of the invention forits rectification.

The device proposed by the invention is different from theelectromagnetic forming devices of the state of the art because it doesnot require an upper female element and a lower female elementaccurately reproducing the final geometry, both the shape and thedimensions, of the entire part to be obtained due to the fact that themagnetic field acts only in those areas in which the part is out of theadmissible tolerances, with the subsequent cost reduction.

It is extremely simple and cheap to manufacture the electromagneticdevice proposed by the invention because it uses at least one block andat least one electromagnetic coil as tools allowing its adaptation toeach type of geometry.

Said at least one block and said at least one electromagnetic coil canbe exchanged, being adapted to each area to be rectified, therefore, iftheir design is taken care of, a same pair formed by a block and anelectromagnetic coil can serve to rectify different parts, being locatedin areas having the same final geometry to be obtained.

Therefore, the cost is much lower than in the case of having to arrangea complete hold-down plate, female element and male element havingexactly the complete final geometry of the entire sheet to be obtained.

This device eliminates the need of having to carry out successivecorrections in the geometry of conventional stamping dies in order toeliminate the springback effect in the part. These corrections aregenerally carried out by means of an iterative correction, trial anderror process with the great cost increase that this entails.

The device of the invention substitutes the mechanical calibrating diewhich can be omitted, with the subsequent saving of space in a factory,the reduction of initial costs due to the removal of a die and thepossibility of use in press lines with one less station.

Furthermore, compared to the device and processes described in Japanesepatents No. JP 2004-122177 and JP 2001-252788, the device of theinvention allows rectifying any type of parts, preferably sheets, ofconducting metallic materials such as steel, in addition to theaforementioned advantages.

DESCRIPTION OF THE DRAWINGS

In order to complement the description being made and with the aim ofaiding in better understanding the features of the invention, accordingto a preferred embodiment thereof, a set of drawings is attached as anintegral part of said description, in which the following has beenrepresented with an illustrative and non-limiting character:

FIG. 1 shows an electric scheme of the discharge circuit comprising thedevice of the invention and allowing the generation of a magnetic fieldfor the rectification of metal parts.

FIG. 2 shows a section of a final geometry to be obtained for a part anda geometry obtained after a conventional stamping process, thespringback effect being observed in the latter, in comparison to thefinal geometry to be obtained.

FIG. 3 shows a section of an elevational view of a schematicrepresentation of the electromagnetic device proposed by the inventionin which the situation of the part to be rectified can be observed.

FIG. 4 shows a section according to a plan view of an embodiment of thedevice of the invention in which three blocks and three electromagneticcoils in three areas to be rectified of the part can be observed on aconventional stamping die base design, in which the simplicity of thedevice object of the invention compared with the complexity of aconventional stamping die can be verified.

FIG. 5 shows an elevational view of the electromagnetic device of theinvention according to the direction A-A of the previous figure.

FIG. 6 shows a section of an elevational view according to section lineB-B shown in FIG. 4, in which a block and an electromagnetic coillocated in correspondence, between which is a part to be rectified, canbe observed.

FIG. 7 shows another section of an elevational view like that of theprevious figure according to section line C-C shown in FIG. 4.

FIG. 8 shows a flow diagram in which the main steps comprising themethod for the geometric rectification of stamped metal parts proposedby the invention can be observed.

PREFERRED EMBODIMENT OF THE INVENTION

In view of the described figures, it can be observed that in one of thepossible embodiments of the invention, the electromagnetic device forthe geometric rectification of stamped metal parts comprises at leastone block (2) configured to receive the impact and contact a side of acertain area to be rectified of a part (1).

The geometry of a surface of said at least one block (2) configured tocontact the part (1) to be rectified exactly corresponds to a desiredfinal geometry (10) in said side of the area to be rectified of the part(1).

In a complementary manner to each at least one block (2), the devicecomprises an electromagnetic coil (5) which is configured to be locatedon a side opposite to said at least one block (2) of a certain area tobe rectified of the part (1).

In the event that a block (2) is located on a first side (12) of thepart (1), then the complementary electromagnetic coil (5) is located ona second side (11) opposite to the first side (12), and vice versa,i.e., in the event that a block (2) is located on the second side (11)of the part (1), then the electromagnetic coil (5) is located on thefirst side (12).

Each at least one electromagnetic coil (5) comprises at least onewinding (6) embedded in a part, preferably a synthetic body offiberglass for example. Said electromagnetic coil (5) has an outersurface opposite to a side of the part (1), having a geometryapproximate to the desired final geometry (10) in the part (1), therebeing a space or clearance between each at least one electromagneticcoil (5) and each at least one block (2) that is less than ten times thethickness of the part (1), with the aim that the action of the magneticfield drives the part (1) for its impact against the block (2).

As depicted in FIGS. 1 and 3, each at least one electromagnetic coil (5)comprises at least one winding (6) connected to a power supply source(7) configured to generate a magnetic field.

Each at least one electromagnetic coil (5) is operatively located suchthat the magnetic field it generates acts in a certain area to berectified of the part (1), acting thereupon and producing an impact ofthe part (1) against the corresponding block (2).

Each at least one winding (6) is connected to a discharge circuitcomprising a capacitor (8), preferably a capacitor bank and a highvoltage circuit comprising a power supply source (7) and trigger startmeans (9) such that when the capacitors (8) are charged and areactivated by means of the trigger start means (9), a transient currentis created in each at least one winding (6) generating the transientmagnetic field.

Said magnetic field induces Foucault currents in the part (1) to berectified, therefore the part (1) is driven in a direction opposite tothat of each at least one electromagnetic coil (5), being pushed againstsaid at least one block (2) such that the side of the areas to berectified of the part (1) in contact with said at least one block (2) isformed acquiring the geometry of said at least one block (2).

As shown in FIGS. 3 to 7, the possibility is considered that said atleast one block (2) and electromagnetic coil (5) are linked both at afirst base (3) and a second base (4), with the aim of serving as asupport.

Likewise, the possibility is considered that said first base (3) andsaid second base (4) comprise moveable closure means to facilitate theremoval of the part (1), the bases being able to be arranged in both ahorizontal and a vertical position.

In the embodiment shown in FIGS. 4 to 7, the device comprises a firstblock (2) located in a complementary manner to a first electromagneticcoil (5) comprising a first winding (6). On the other hand, the devicecomprises a second block (2′) located in a complementary manner to asecond electromagnetic coil (5′) comprising a second winding (6′).Finally, the device comprises a third block (2″) located in acomplementary manner to a third electromagnetic coil (5″) comprising athird winding (6″) arranged perpendicular to the first winding (6) andto the second winding (6′).

As can be seen in FIG. 6, the first winding (6) has a geometry adaptedto the curved area of the final geometry (10) to be obtained in thepart.

In this embodiment, the first block (2), the third block (2″) and thesecond electromagnetic coil (5′) are linked to the first base (3)whereas the second block (2′), the first electromagnetic coil (5) andthe third electromagnetic coil (5″) are linked to the second base (4).

Finally, the possibility is contemplated that the device comprises atleast one driver (13) consisting of a sheet of material with a highcopper content, as can be seen in FIG. 3, located between said at leastone electromagnetic coil (5) and the part (1) to be rectified, with theaim of reducing the energy demands of the device to obtain a certaingeometry in a part (1) to be rectified.

A second aspect of the invention relates to a method for the geometricrectification of stamped metal parts with an electromagnetic device likethe one previously described.

The method of the invention is carried out starting from the metal partto be rectified, i.e., a sheet which has already been mechanicallystamped in a traditional press, with the aim of rectifying the geometryof the part in those areas in which the part is out of the establishedtolerances.

As can be observed in FIG. 8, the method for the geometric rectificationof stamped metal parts object of the invention comprises the followingsteps:

A first step (A) comprising to place a stamped part (1) with each areato be rectified operatively located between a block (2) and anelectromagnetic coil (5) said part (1) being conveniently separated fromthe block (2) which is separated from the complementary electromagneticcoil (5) by a distance not greater than ten times the thickness of thepart (1).

A second step (B) comprising to generate a magnetic field configured toact in the areas to be rectified of the part (1) such that they adopt arequired final geometry (10) when the part (1) impacts against eachblock (2).

A third step (C) comprising to remove the already rectified part.

The possibility is considered that the method comprises an intermediatestep which would be carried out before the second step (B) andcomprising to place at least one driver (13), i.e. a sheet of materialwith a high copper content, between said at least one electromagneticcoil (5) and the part (1) to be rectified, with the aim of reducing theenergy demands of the method.

In view of this description and set of drawings, a person skilled in theart will understand that the embodiments of the invention which havebeen described can be combined in many ways within the object of theinvention. The invention has been described according to some preferredembodiments thereof, but for a person skilled in the art it will beevident that many variations can be introduced in said preferredembodiments without surpassing the object of the claimed invention.

1. An electromagnetic device for the geometric rectification of stampedmetal parts comprising: at least one block configured to contact oneside of an area to be rectified of a stamped metal part, the geometry ofa surface of said at least one block configured to contact the partcoinciding with a desired final geometry in said side of the area to berectified of the part, at least one electromagnetic coil configured tobe located on a side opposite to said at least one block of said area tobe rectified of the part, at least one embedded winding that compriseseach at least one electromagnetic coil, said winding being configured togenerate a magnetic field operatively configured to act on the part andproduce its impact against the corresponding block, a space between eachat least one electromagnetic coil and each at least one block notgreater than ten times the thickness of the part.
 2. An electromagneticdevice for the geometric rectification of stamped metal parts accordingto claim 1, wherein each at least one block and each at least oneelectromagnetic coil are linked to a first base and to a second base. 3.An electromagnetic device for the geometric rectification of stampedmetal parts according to claim 2, wherein the first base and the secondbase comprise moveable closure means.
 4. An electromagnetic device forthe geometric rectification of stamped metal parts according to claim 2,comprising: a first block located in a complementary manner to a firstelectromagnetic coil comprising a first winding, a second block locatedin a complementary manner to a second electromagnetic coil comprising asecond winding, a third block located in a complementary manner to athird electromagnetic coil comprising a third winding arrangedperpendicular to the first winding and to the second winding.
 5. Anelectromagnetic device for the geometric rectification of stamped metalparts according to claim 4, wherein the first block, the third block andthe second electromagnetic coil are linked to the first base whereas thesecond block, the first electromagnetic coil and the thirdelectromagnetic coil are linked to the second base.
 6. Anelectromagnetic device for the geometric rectification of stamped metalparts according to claim 1, wherein the area to be rectified of the part(1) corresponds to virtually the entire surface of said part.
 7. Anelectromagnetic device for the geometric rectification of stamped metalparts according to claim 1, comprising at least one driver consisting ofa sheet of a material with a high copper content, located between saidat least one electromagnetic coil and the part to be rectified, in orderto reduce the energy demands of the device for obtaining a certaingeometry in a part to be rectified.
 8. An electromagnetic device for thegeometric rectification of stamped metal parts according to claim 1,wherein at least one electromagnetic coil comprises a body of syntheticmaterial, said body having at least one surface configured to be locatedopposite to a side of the part with a geometry correspondingsubstantially to the desired final geometry in said side of thementioned area to be rectified of the part.
 9. A method for thegeometric rectification of stamped metal parts with a device accordingto claim 1, comprising the following steps: a first step comprising toplace a stamped part with each area to be rectified operatively locatedbetween a block and an electromagnetic coil, said part beingconveniently separated from the block which is separated from thecomplementary electromagnetic coil by a distance not greater than tentimes the thickness of the part, a second step comprising to generate amagnetic field configured to act in the areas to be rectified of thepart such that they adopt a required final geometry when the partimpacts against each block, a third step comprising to remove thealready rectified part.
 10. A method for the geometric rectification ofstamped metal parts according to claim 9, comprising an intermediatestep, prior to the second step, comprising to place at least one driverbetween said at least one electromagnetic coil and the part to berectified.
 11. A method for the geometric rectification of stamped metalparts according to claim 10, wherein the driver comprises a sheet ofmaterial with a high copper content.